Relationship between labour analgesia modalities and types of anaesthetic techniques in categories 2 and 3 intrapartum caesarean deliveries.

General anesthesia (GA) is typically recommended for category 1 emergency cesarean delivery (CD). For categories 2­4 emergencies, either regional or GA can be used. The factors influencing the choice of anesthetic technique in these categories remain poorly understood. We analyzed the association between the type of labor analgesia and subsequent anesthetic techniques employed for intrapartum categories 2 and 3 CD. In a prospective longitudinal cohort study, 300 women were consequently enrolled and categorized according to Lucas's classification of CD urgency. The techniques of anesthesia (GA, spinal, and epidural anesthesia [EA]) employed for CD were analyzed with respect to labor analgesia methods (remifentanil patient-controlled analgesia [remifentanil-PCA], EA, and nitrous oxide [N2O]). EA was the most frequent analgesic option (43.8%), followed by remifentanil-PCA (20.7%) and N2O (5.1%), while 30.4% of parturient women received no analgesia. All anesthetic methods showed a significant relationship with analgesic modalities (P < 0.001). Remifentanil-PCA was associated with a higher incidence of GA. Contraindication to EA was the primary factor related to the transition from remifentanil-PCA to GA. Most parturients who received EA were successfully converted to EA. Spinal anesthesia was the most common technique in women using N2O and those without labor analgesia. GA was associated with lower 5-min Apgar scores. The method of labor analgesia was associated with the anesthesia technique employed for categories 2 and 3 CD. This finding may guide patient counseling and intrapartum anesthetic planning. However, the analysis should be cautiously interpreted as the selection of anesthesia is a complex decision influenced by several clinical considerations.

Maternal Fatigue after Postpartum Anemia Treatment with Intravenous Ferric Carboxymaltose vs. Intravenous Ferric Derisomaltose vs. Oral Ferrous Sulphate: A Randomized Controlled Trial.

(1) Background: Postpartum anemia is a common maternal complication and is recognized as a cause of impaired quality of life, reduced cognitive abilities, and fatigue. Efficient iron supplementation for the treatment of postpartum anemia is an essential component of high-quality maternal care. The optimal mode of iron supplementation has not been determined yet, whether oral or intravenous. The objective of this study was to compare postpartum anemia treatment with intravenous ferric carboxymaltose, intravenous ferric derisomaltose, and oral ferrous sulfate. (2) Methods: A single-center, open-label, randomized controlled trial. Women with hemoglobin < 100 g/L within 48 h postpartum were randomly allocated to receive intravenous ferric carboxymaltose, intravenous ferric derisomaltose, or oral ferrous sulfate. Intravenous iron was given in one or two doses, while ferrous sulfate was given as two 80 mg tablets once daily. The primary outcome was maternal fatigue measured by the Multidimensional Fatigue Inventory (MFI) six weeks postpartum. Hemoglobin, ferritin, and transferrin saturation levels were analyzed as secondary outcomes. A Kruskal-Wallis test was used for group comparison (p < 0.05 significant). (3) Results: Three hundred women were included. The MFI score at six weeks postpartum did not differ between groups (median 38 (inter-quartile range (IQR) 29-47) in the ferric carboxymaltose group, median 34 (IQR 26-42) in the ferric derisomaltose group, and median 36 (IQR 25-47) in the ferrous sulfate group; p = 0.26). Participants receiving oral iron had lower levels of hemoglobin (135 (131-139) vs. 134 (129-139) vs. 131 (125-137) g/L; p = 0.008), ferritin (273 (198-377) vs. 187 (155-246) vs. 24 (17-37) µg/L; p < 0.001) and transferrin saturation (34 (28-38) vs. 30 (23-37) vs. 24 (17-37) %; p < 0.001) than those receiving ferric carboxymaltose or ferric derisomaltose. (4) Conclusions: Intravenous ferric carboxymaltose, intravenous ferric derisomaltose, and oral ferrous sulfate had similar impacts on maternal fatigue at six weeks postpartum despite improved laboratory parameters in the intravenous groups.

Fetal death from SARS-CoV-2 mediated acute placental failure.

INTRODUCTION: We demonstrate the nonlinear severity of symptoms of SARS-CoV-2 infection in the mother leading to fetal death after acute placental failure. METHODS: Careful clinical evaluation, real-time RT-PCR molecular microbiologic testing, isolation of a viable virus, and autopsy with histologic results were used to investigate the possible vertical transmission of SARS-CoV-2 infection from mother to fetus. RESULTS: Histologic changes in the placenta correlate with SARS-CoV-2 infection. Total nucleic acid isolated from vaginal swabs, fresh placental tissue, and deparaffinized tissue showed a high viral load of SARS-CoV-2. Complete genome sequencing confirmed the presence of the SARS-CoV-2 Delta variant. DISCUSSION: Several methods have been used to confirm SARS-CoV-2-mediated acute placental failure, all of which were conclusive. It should be noted that careful periodic fetal well-being checks are required in women infected with SARS-CoV-2, regardless of the severity of symptoms. Most of the cases described with fetal death occurred in the third trimester.

Comparison of "growth promoted" and "normally grown" dichorionic-diamniotic twins: A population-based study.

Objectives: Macrosomia in singleton pregnancies and associated risks have been well characterized. Less is known about the outcomes of macrosomic newborns in twin pregnancy.Objective of this study was to compare maternal characteristics and perinatal outcomes of "growth promoted twins" (twin pairs with a total twin birth weight above 90th percentile) to "normally grown twins" (twin pairs with a total twin birth weight between 50th and 90th percentile). Methods: We evaluated data (maternal characteristics and perinatal outcomes) of dichorionic-diamniotic twins born at 34 weeks of gestational age or later over a sixteen-year period (2002-2018) in two birth weight groups. We excluded twin pairs born before 34th week of gestation and discordant twin pairs. We used data from the Slovenian National Perinatal Information System.To define the percentiles, twin-specific growth curves have been used. Results: Our study population consisted of 390 twin pregnancies with a twin total birth weight over 90th percentile and 1618 pregnancies with a total twin birth weight between 50th and 90th percentile for gestational age. Women in "growth promoted" twin group were significantly taller, heavier and more often multiparous. There was a higher incidence of gestational diabetes (10.8% vs 7.3%, OR 1.53 95% CI 1.06 - 2.22), a lower rate of caesarean births (48.2% vs 53.9%, OR 0.80 CI 0.64 - 0.99) and lower rate of assisted reproduction (21.0% vs 27.1%, OR 0.71 CI 0.55 - 0.93) in women in "growth promoted" twin group. There were no statistically significant differences in neonatal outcomes in both groups. Conclusion: In contrast to macrosomia in singletons, macrosomia in twins does not appear to increase the risk for adverse perinatal outcomes.

Publisher Correction: An improved method of crafting a multi-electrode spiral cuff for the selective stimulation of peripheral nerves.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

An improved method of crafting a multi-electrode spiral cuff for the selective.

This article reviews an improved methodology and technology for crafting a multi-electrode spiral cuff for the selective activation of nerve fibres in particular superficial regions of a peripheral nerve. The analysis, structural and mechanical properties of the spot welds used for the interconnections between the stimulating electrodes and stainless-steel lead wires are presented. The cuff consisted of 33 platinum electrodes embedded within a self-curling 17-mm-long silicone spiral sheet with a nominal internal diameter of 2.5 mm. The weld was analyzed using scanning electron microscopy and nanohardness tests, while the interconnection was investigated using destructive load tests. The functionality of the cuff was tested in an isolated porcine vagus nerve. The results of the scanning electron microscopy show good alloying and none of the typical welding defects that occur between the wire and the platinum foil. The results of the destructive load tests show that the breaking loads were between 3.22 and 5 N. The results of the nanohardness testing show that the hardness of the weld was different for the particular sites on the weld sample. Finally, the results of the functional testing show that for different stimulation intensities both the compound action potential deflection and the shape are modulated.

Analysis of compound action potentials elicited with specific current stimulating pulses in an isolated rat sciatic nerve.

The ability to selectively stimulate Aα, Aß-fibers and Aδ-fibers in an isolated rat sciatic nerve (SNR) was assessed. The stimulus used was a current, biphasic pulse with a quasitrapezoidal cathodic phase and rectangular anodic phase where parameters were systematically varied: intensity of the cathodic phase (ic); width of the cathodic phase (tc); width of the cathodic exponential decay (texp) and time constant of the exponential decay (τexp). A SNR was stimulated using a pair of hook electrodes while conduction velocity (CV) and compound action potentials (CAP) were measured at two sites along the SNR using another two pairs of electrodes. Results showed that the highest CAP1 (8.5-9 mV), shall be expected when parameters of the stimulus were within the following range: ic=3.8-4 mA, tc=350-400 µs and texp=330-440 µs. Results also showed that with ascending tc and texp, CV of the corresponding superficial region of the SNR was reduced in both, conduction velocity of CAP1 and conduction velocity of CAP2. It was concluded that action potentials (APs) were activated in the Aß-fibers and Aδ-fibers along with a slight AP inhibition in the Aß-fibers. The obtained results, could serve as a tool for developing multi-electrode systems that potentially enable fiber-type selective stimulation of nerve fibers.

Evaluation of the Efficacy and Robustness of a Second Generation Implantable Stimulator in a Patient With Hemiplegia During 20 Years of Functional Electrical Stimulation of the Common Peroneal Nerve.

We evaluated the efficacy and robustness of a second generation implantable stimulator for correcting drop foot (DF) in a patient with left-sided hemiplegia over 20 years of functional electrical stimulation (FES) of the common peroneal nerve (CPN). Dorsal flexion and eversion of the affected foot was partially restored by FES of the superficial region of the CPN innervating mostly the tibialis anterior (TA) and partly peroneus longus (PL) and peroneus brevis (PB) muscles. The reasons for implant failure during the long-term follow-up assessment were analyzed and resolving procedures were identified. The stimulator had an average failure rate of once every three years, due to repetitive mechanical load on the lead wires of its internal and/or external unit, and had to be serviced once per year to replace the heel switch integrated into the shoe sole. FES-associated mechanical trauma to the CPN elicited a thickening of the connective tissue around the CPN and a slightly compromised conduction velocity of the CPN. FES of the CPN, with the second generation implantable stimulator, improved gait parameters of the affected leg during the 20 years period. Long-term, daily FES enables a functional and reliable recruitment of nerve fibers, thus providing a sufficient dorsal flexion and optimal eversion of the affected foot to sustain unassisted, almost normal gait. Therefore, the presented implant is suitable for very long-term FES of the CPN.

Electrochemical and Electrophysiological Performance of Platinum Electrodes Within the Ninety-Nine-Electrode Stimulating Nerve Cuff.

The trend in neural prostheses using selective nerve stimulation for electrical stimulation therapies is headed toward single-part systems having a large number of working electrodes (WEs), each of which selectively stimulate neural tissue or record neural response (NR). The present article reviews the electrochemical and electrophysiological performance of platinum WE within a ninety-nine-electrode spiral cuff for selective nerve stimulation and recording of peripheral nerves, with a focus on the vagus nerve (VN). The electrochemical properties of the WE were studied in vitro using the electrochemical impedance spectroscopy (EIS) technique. The equivalent circuit model (ECM) of the interface between the WE and neural tissue was extracted from the EIS data and simulated in the time domain using a preset current stimulus. Electrophysiological performance of in-space and fiber-type highly selective vagus nerve stimulation (VNS) was tested using an isolated segment of a porcine VN and carotid artery as a reference. A quasitrapezoidal current-controlled pulse (stimulus) was applied to the VN or arterial segment using an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate B-fibers and minimize the stimulation of A-fibers. The EIS results revealed capacitive charge transfer predominance, which is a highly desirable property. Electrophysiological performance testing indicated the potential existence of certain parameters and waveforms of the stimulus for which the contribution of the A-fibers to the NR decreased slightly and that of the B-fibers increased slightly. Findings show that the design of the stimulating electrodes, based on the EIS and ECM results, could act as a useful tool for nerve cuff development.

Structural characterization of platinum foil for neural stimulating electrodes.

OBJECTIVE: The objective of this study was to investigate the structural properties of a cold-rolled platinum foil used to manufacture multi-electrode spiral nerve cuffs. METHODS: To attain this objective, 0.03-mm-thick cold-rolled platinum foil strips with 99.99 wt% purity were used. The resistivity measurements were made using a 4-point probe technique in which the strips were subjected to dynamic annealing in an argon atmosphere. The stored energy of platinum was recorded in an argon atmosphere using differential scanning calorimetry (DSC). Finally, the microstructure of the strips was investigated by optical microscopy. RESULTS: In the resistivity measurements, a small change is observed at ~280°C. This change could be explained as the partial recovery elicited by the decrease of dislocation density. Above 500°C, a significant decrease in resistivity was recorded, and the decrease reached a maximum at ~750°C. These results are consistent with the recrystallization trend detected in DSC, namely the DSC measurement detected very weak heat release during recrystallization, which was actually accumulated during the cold-working. This exothermal peak occurred in the temperature range 380-800°C.

Electrochemical performance of platinum electrodes within the multi-electrode spiral nerve cuff.

In this study, the electrochemical performance of platinum electrodes within a multi-electrode spiral cuff to be used for selective nerve stimulation was investigated. The original cuff, simplified into a half-cuff, contained a single row of nine electrodes (0.5 × 2 mm) at a distance of 2 mm from its inner surface. Cyclic voltammetry was used to investigate the electrochemical reactions at the electrode-electrolyte interface, to define a potential window within which the electrode could be safely used in selective nerve stimulation, to calculate the charge injection capacity and cathodal charge storage capacity. Voltage transients retrieved during excitation with quasitrapezoidal biphasic current pulses, tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment, were used to determine the maximum polarization across the electrode-electrolyte interface and to calculate cathodic charge injection capacity of the electrode. The results show that the most negative and most positive potentials across the electrode-electrolyte interface reached -0.54 and 0.59 V; these did not exceed the safe potential limits for water electrolysis. Furthermore, the time integral of the cathodic current by cyclic voltammetry measured over the potential range of water electrolysis, actually representing the cathodal charge storage capacity, was approximately -4 mC cm(-2). The charge injection capacity, representing the maximum charge density injected in a current stimulation pulse, using only reversible processes, however, was around 75 µC cm(-2). In conclusion, both, the tested stimulation pulse and electrode are suitable for efficient and safe selective nerve stimulation.

Alternative paradigm of selective vagus nerve stimulation tested on an isolated porcine vagus nerve.

Alternative paradigm for spatial and fibre-type selective vagus nerve stimulation (VNS) was developed using realistic structural topography and tested in an isolated segment of a porcine cervical left vagus nerve (LVN). A spiral cuff (cuff) containing a matrix of ninety-nine electrodes was developed for selective VNS. A quasitrapezoidal stimulating pulse (stimulus) was applied to the LVN via an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate the B-fibres, minimizing stimulation of the A-fibres and by-passing the stimulation of the C-fibres. To assess which fibres made the most probable contribution to the neural response (NR) during selective VNS, the distribution of conduction velocity (CV) within the LVN was considered. Experimental testing of the paradigm showed the existence of certain parameters and waveforms of the stimulus, for which the contribution of the A-fibres to the NR was slightly reduced and that of the B-fibres was slightly enlarged. The cuff provided satisfactory fascicle discrimination in selective VNS as well as satisfactory fascicle discrimination during NR recording. However, in the present stage of development, fibre-type VNS remained rather limited.

Evaluation of NiTi Superelastic Retraction Coil Springs for orthodontic tooth movement in rats.

The purpose of this investigation was to assess mechanical properties of Superelastic Retraction Coil Springs for orthodontic use. To reach a goal, a test frame, comprising measuring force transducers was developed. To perform metallographic analyses of the nickel-titanium wire the samples of Superelastic Retraction Coil Springs were observed by scanning electron microscope. For in vivo testing, twenty male Wistar rats, 11-12 weeks of age, were used (Group I with Superelastic Retraction Coil Springs, Group II controls). To simulate human distraction as close as possible, all the applied Superelastic Retraction Coil Springs were modified. The Superelastic Retraction Coil Springs creating a constant force of 25 cN were then attached between the upper left first molars and upper left incisors. Results showed that the reproducible force of 25 cN was shown over a range of 1-11 mm extension. Results also showed that the distance between aforementioned teeth, measured on days 0, 7, 14, 21, 24, 32, 37 and 40, decreased in Group I. Contrary, in Group II the distance between the teeth increased during the study (p<0.001).

Selective stimulation of autonomic nerves and recording of electroneurograms in a canine model.

The article presents the results of modeling, design, and experimental testing of a multielectrode spiral cuff (CUFF) to determine to what extent a CUFF could be used for selective stimulation of different types of nerve fibers within particular compartments and for selective recording of electoneurograms (ENGs) from particular compartments of the peripheral autonomic nerve. The CUFF was implanted on the left cervical vagus nerve (LVN) of a dog. The relative positions of the particular nerve regions that innervated the cardiovascular (CV) and respiratory system (RS) were identified by delivering the stimuli to the particular group of three electrodes (GTE). The stimuli caused both selective stimulation of mainly B fibers within the particular compartments, and differential block of A fibers by membrane hyperpolarization. It was shown that when the stimuli were delivered to GTE9, the heart rate began to fall and when the stimuli were delivered to GTE4, the rate of breathing decreased. The defined and randomly chosen GTEs were used also as recording GTEs while CV or RS were stimulated by carotid artery massage, epinephrine injection, and noninvasive positive end-expiratory pressure ventilation (NIPEEPV). Results demonstrate that the function of a particular internal organ can be modulated via the selective stimulation of the innervating compartment of the peripheral nerve. Results also showed that stimulations elicited site-specific changes in ENG power spectra recorded from the particular compartments of the LVN.